Process for obtaining alpha-beta, deltaepsilon unsaturated esters



Unite This invention is an improvement in processes for reacting allyl derivatives with acetylene, carbon monoxide,

and water or alcohols, to produce alph-beta, delta-epsilon, unsaturated carboxylic compounds.

This application is directed to an improvement in the inventions described in Chiusoli applications Serial No. 765,739, filed October 7, 1958; and Serial No. 862,067, filed December 28, 1959.

, In said processes carbon monoxide is derived partially from nickel carbonyl which is introduced in amount suflicient to maintain the reaction. The reaction resented schematically as follows:

wherein R is hydrogen or a methyl or its homologues, and R is H or an alkyl radical. The reaction holds also in the case where R is phenyl. It also holds with primary chloroderivatives that are substituted at the double bond with alkyls, secondary chloroderivatives,

compounds which are polyfunctional in respect to the allyl group, or compoundscontaining non-reactive substituents bound to the alkyl sub-sub'stituents.

The present invention relates to a new method of execution of the reaction of allyl chloroderivatives with acetylene and carbon monoxide without need for recourse to use of nickel-carbonyl. Instead, subdivided nickel is employed in the presence of thiourea.

This is surprising since the use of subdivided nickel, alone or in the presence of sulfides which promote the formation of nickel carbonyl in situ, produces very poor results. In contrast, the use of thiourea, which with allyl chloroderivatives readily forms the corresponding pseudothiouronium salts:

makes it possible to obtain satisfactory yields.

The advantage of this method is evident when it is considered that the preparation of nickel carbonyl requires a separate plant, Whereas'divided nickel can be prepared economically by many methods. It has been found that Raney nickel, the nickel obtained by decomposition of nickel formate, the nickel obtained by reduction of nickel hydroxide with hydrogen, and the nickel formed in the system comprised of subdivided iron and nickel chloride, can be employed satisfactorily. In the latter case, it is satisfactory to use nickel chloride in proportions lower than 20% in respect to the iron, which displaces nickel continuously from the nickel chloride formed during the reaction. The iron is obtained without any difliculty by reduction of oxides, or by grinding of common metal iron followed by sieving on a 16,000- mesh sieve. When using the latter iron, operation under inert gas is preferable, since said iron is pyrophoric. The

States Patent is repfor the use as drying oils.

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carbonyl also takes place during the reaction, the catalyst is formed directly from nickel, without passing through nickel carbonyl.

Nickel with acetylene probably forms complexes of the following type:

in which a CO group can be replaced by a thiourea molecule. The thiourea, freed by decomposition of the complex, forms addition compounds with NiCl and HCl.

Thiourea is not used in stoichiometric amounts. Suitable proportions are readily determined experimentally. The preferred range is 0.1 to 0.5 mol per mole of chloroderivative.

The amount of thiourea required from the reaction with Raney nickel is higher than with nickel from the system iron-nickel chloride for the reason that Raney nickel contains active hydrogen which is eliminated by reactivation with thiuorea.

However it has been found that the use of both thiourea and metals can be considerably lowered by neutralising the hydrochloric acid freed during the reaction. -As neutralising agents sodium, potassium, calcium and magnesium hydroxides and carbonates and similar are 'mentioned more general cases, it is most advantageous in the preparation of esters from primary chloroderivatives containing up to 20 carbon atoms, of the type:

wherein R R and R are hydrogen, or methyl, or higher homologues, such as ethyl, propyl, butyl, hexyl. The aliphatic alcohols used preferably contain 1 to 5 carbon atoms. The most convenient temperature range is between 10 and +50 C., and preferably between 10 and 30 C. A dilution in the reaction solution higher than 8 parts of solvent per part of chloroderivative is preferable.

The products obtained belong to the same class of 2,5-dienic esters of the aforementioned main applications. It should however be noted that the increase in the amount of thiourea and depending on the nature of the chloroderivative, and on the reaction conditions, and in the thermal treatment during the separation of the products, can result in the formation (due to the isomerizing activity of the thiourea), not only of compounds containing the double bond conjugated with the carboxy group in the cis form, but also of a small amount of product in the trans form and with conjugated double bonds.

Tautomerism is a typical property of these products. For example the 2,5 heptadienoic ester is easily accompanied by the tautomer 3,5 to an extent of l0 15%.

This is not harmful, since one of the main uses of this class of products is connected with their transformation into conjugated products, thus making them suitable Another use is by hydrogenation to saturated esters to be employed, for instance, in the field of plasticizers, said hydrogenation occurring equally well on the isomers. The alcohol whose ester is desired and the subdivided nickel, as such or in the form of a mixture with divided or powdered iron, are placed in the reaction vessel.

The reactor is washed with nitrogen while agitating. Nickel or iron are added in amounts higher than that consumed by the reaction. The excess is filtered off at the end of the reaction. A stream of carbon monoxide and acetylene is passed through the solution while the latter is brought to the desired temperature of reaction by heating or cooling.

The ratios of acetylene to carbon monoxide vary depending on the needs of the reaction, i.e. depending on the more or less catalytic character connected with the reactivity of each chloroderivative. By working in a closed cycle, the acetylene/carbon monoxide ratio is adjusted, on the basis of the analysis of the gases, depending on the reaction consumption. For the sake'of ease of execution in the laboratory, the Examples 1-7 reported below were carried out without recycling the gases, while maintaining a 1:1 ratio, which generally avoids the stopping of the reaction due to defect of acetylene, or any excessive formation of side products due to the excess of acetylene. The process can be carried out also (see Example 9 below) with recycling otthe reaction gases, so as to maintain a concentration more suitable for the reaction. A mixture of chloroderivative and thiourea in alcohol is introduced slowly into the reaction vessel while controlling the temperature. Thiourea can be introduced first. The duration of the addition depends on the reactivity of the chloroderivative.

The reaction is generally complete within a few hours. The gas is then removed by a stream of nitrogen, the nickel and iron excess being then filtered off and the alcohol distilled together with the non-converted product, with duplication products of the allyl radical of the chloroderivative and with small amounts of esters which in some cases distill easily with water, if this is present in the alcohol. The recovery can be carried out by salting out the distillate with a saturated calcium chloride solution. The oily layer is taken up again with a little water, decanted or collected in ether, washed with water, dried and distilled. The distillation is preferably carried out under vacuum, which facilitates obtaining the esters,

In order to accomplish isomerisation to conjugated dienic acid the products are treated to refiux with alkali, e.g. aqueous NaOH, following the known art. In order to obtain hydrogenated compounds the products are cataly-tically hydrogenated at room temperature over Raney nickel or Pd catalysts by known methods.

The examples reported hereinbelow illustrate preferred embodiments of the present invention, and are not intended to limit its scope.

Example 1 400 ml. of methanol and 30 ml. of wet Raney nickel are placed in a 1-liter S-necked glass flask provided with thermometenagitator, inlet tube for the gases, reflux condenser and separatory funnel. The apparatus is flushed with nitrogen, the suspension is agitated and bubbling of carbon monoxide and acetylene (CO flowrate 3 liters per hour; C H flow-rate 31 liters per hour) is started; the temperature of the suspension is adjusted to C. by a cooling bath, which also maintains this temperature during the reaction.

When the reaction temperature is reached, dropwise addition of the following solution is started:

40 g. of allyl chloride 8 g. of thiourea, and 180 ml. of methanol The dropwise addition is carried out through a dropping funnel, regulated so that the solution falls into the flask within about 6 hours. At the end of said addition the flow of CO and C H is continued for about 30 minutes and then, when the reaction is completed, the gases are removed by a stream of nitrogen.

The excess of Raney nickel is filtered. The filtrate is placed in a flask and, by heating on a water-bath, is distilled to remove the alcohol together with a little crude product. The distillation residue is taken up again with water. An oily layer is separated and collected in ethyl ether. The residual liquid contains 7.7 g. of nickel in the salt form. Upon salting out with the same volume of a saturated aqueous calcium chloride solution, an upper layer is separated from the distillate. The upper layer is collected in ethyl ether by shaking in a separating funnel, and is added to the preceding extract.

The two mixed ether extracts are distilled on an oil bath by first separating the distillation heads up to C. and then, at 6366 C. (34 mm. Hg), a fraction of 25 g. containing the methyl ester of 2,5-hexadienoic acid separates.

Example 2 400 ml. of methanol and 30 ml. of wet Raney nickel are placed in a IOOO-ml. glass flask provided with thermometer, agitator, inlet pipe for the gases, reflux condenser and separating funnel. The apparatus is flushed with nitrogen, the suspension is agitated, and bubbling of carbon monoxide and acetylene (CO flow rate 3 liters per hour, C H flow rate 3 l./h.) is started.

. When the temperature of the suspension is stabilized at 20 C., the dropping of the following solution is started, in the dropping funnel:

40 g. of 96% methallylchloride 24 g. of thiourea ml. of methanol The dropping is regulated so that the solution falls into the flask Within 6 hours. The passage of CO and C H is continued for about 30 minutes after the end of dropping. The gases are then removed by a stream of nitrogen.

By operating as in Example 1, a fraction of 34 g. containing the methyl ester of 5-methyl-2,5-hexadienoic acid (boiling point 65-69 C./l8 mm. Hg) is obtained; 3 grams of nickel appear to be transformed into chloride.

Example 3 400 ml. of methanol, 15 g. of subdivided iron and 5 g. of NiCl .H O are placed in a 1000 ml. glass flask provided with thermometer, agitator, reflux condenser and separating funnel. After flushing with nitrogen, the suspension is agitated, and bubbling of CO and C H (CO'fiow rate 3 liters per hour; C H flow rate 3 l./h.) is started. While keeping the suspension at 30 C., a solution consisting of:

40 g. of methallylchloride 24 g. of thiourea 150 ml. of methanol is added dropwise within 5 hours, from the dropping funnel. After 6 hours the gases are removed by a stream of nitrogen. By operating as in the preceding examples, 35 g. containing the methyl ester of 5-methyl-2,5-hexa dienoic acid(boiling point 65-69 C./l8 mm. Hg) are obtained. 3.5 g. of iron and 0.75 g. of nickel are found in the form of chlorides.

Example 4 A 14 g. of thiourea and 20 ml. of wet Raney nickel are placed in a 1000 ml. flask provided with thermometer, agitator, gas inlet tube, reflux condenser and separating tunnel, containing400 ml. of methyl alcohol; a temperature increase of 10? C. takes place. After flushing with nitrogen, the suspension is agitated, and bubbling of CO and C H (CO flow rate of 3 liters per hour; C H flow rate 3 l./h.) is started. The suspension iskept at 10 C. and a solution containing 40 g. of crotyl chloride, and ml. methanol is dropped from the separating funnel within 5 hours.

By operating as in the preceding examples, 40 g. containing the methyl ester of -2,5-heptadienoic acid (boiling point 72-75 C./20 mm. Hg) are obtained. 5.6 g. of nickel appear to be transformed into chloride.

Example 5 400 ml. of methanol, 15 g. of divided iron and 5 g. of NiCl .6H O are placed in the flask of the preceding examples. After flushing with nitrogen, the suspension is agitated, and bubbling of CO and C H (CO flow rate 3 liters per hour, C H flow rate 3 l/h.) is started. The suspension is kept at 20 C. and a solution consisting of 40 g. of crotyl chloride 16 g. of thiourea 180 ml. of methanol is dropped from the separating funnel Within 5 hours. After 6 hours the gases are removed by a stream of nitrogen. By proceeding as in the preceding examples, 31 g. containing the methyl ester of 2,5-heptadienoic acid (boiling point 72-75 C./ 20 mm. Hg) are obtained.

Example 6 400 ml. of methanol and 30 ml. of wet nickel obtained by reducing nickel hydroxide in aqueous phase at 100- 120 C. under 50 atms. are introduced into the flask of the preceding examples. After flushing with nitrogen, the suspension is agitated, and bubbling of CO and C H (CO flow rate 3 liters per hour, C H flow rate 3 l./h.) is started. Temperature is kept at 30 C. and a solution consisting of 30 g. of crotyl chloride g. of thiourea, and 180 ml. of methanol is dropped from the separating funnel within 5 hours. After 6 hours the gases are removed by a stream of nitrogen. By operating as in the preceding examples, 16 g. containing the methyl ester of 2,5-heptadienoic acid (boiling point 7275 C./20 mm. Hg) are obtained. 4 g. nickel have been transformed into the chloride.

Example 7 100 ml. of methanol and 7 ml. of wet Raney nickel are placed in a 500 ml. flask provided with a thermometer, agitator, gas inlet tube, reflux condenser and separating funnel. After flushing with nitrogen, the suspension is agitated, and bubbling of CO and C H (CO flow rate 2 liters per hour, C H flow rate 2 l./h.) is started. The suspension is kept at 20 C. while a solution consisting of:

13.5 g. of 5,5-dimethyl-2-hexenyl chloride 4.0 g. of thiourea, and 100.0 g. of methanol is dropped from the separating funnel within 5 hours. After 6 hours the suspension is flushed with nitrogen. By operating as in the preceding examples, 10 g. of methyl ester of 8,8-dimethyl-2,S-nonandienoic acid (boiling point 97-l00 C./8 mm. Hg) are obtained. 2.5 g. of nickel were transformed into chloride.

Example 8 800 ml. of methanol, 10 g. of NiCl .6H O, 7 g. of iron, pulverized and sieved under carbon dioxide on a 16,000- mesh sieve, 4 g. of thiourea and g. of basic magnesium carbonate (MgCO .Mg(OH) .5H O, are placed in a flask provided with a mechanical agitator, a reflux condenser, a separating funnel and a gas inlet tube. After flushing with nitrogen and carbon monoxide, a stream of 4 l./h. CO and of 4 l./h. C H is introduced at 30 C. for 6 hours. At the same time from the separating funnel 40 g. of 98% commercial methallyl chloride mixed with 100 ml. of methanol are dropped from the separating funnel for 5 hours.

The mixture is discharged and filtered. The filtrate is distilled, the residue is treated wtih water acidified with sulfuric acid and collected in ether. After drying on sodium sulfate and distilling, 39.2 g. of distillate at 65-69" C./ 18 mm. Hg, containing 5-methyl-2,5-hexadienoic acid methyl ester are obtained, the residue amounting to 3.2 g.

Example 9 800 ml. of methanol, 10 g. of NiCl .6H O, 7 g. of

iron powdered and sieved on a 16,000-mesh sieve, 4 g. of thiourea and 6.5 g. of MgO are introduced into the flask of the preceding example. The reaction is carried out at 30 C. with 30 g. of methallyl chloride, and the gases are recycled by a circulation pump. The cycle is kept under a pressure of 20 ml. water above the atmospheric pressure. After careful flushing with nitrogen, carbon monoxide and then acetylene are introduced, the acetylene concentration being gradually increased from the ini-- tial 33% to 60% after 6 hours. The mixture is discharged and filtered. The distillation residue is taken up with water acidified with sulfuric acid and is collected in ether. After drying on sodium sulfate and distilling, 32 g. containing 5-methyl-2,5- hexadienoic acid methyl ester are obtained at 65-69 C./ 18 mm. Hg. The residue amounts to 2.7 g.

Example 10 800 ml. of methyl alcohol, 7 g. iron pulverized and sieved on a 16,000-mesh sieve, 10 g. of nickel chloride hexahydrate, 4 g. of thiourea and 21 g. of

are placed in the flask of Example 8. 4 l./h. of CO and 4 l./h. of C H are then introduced at 30 C. for 6 hours, and 40 g. of crotyl chloride in ml. of methanol are dropped from the separating funnel within 5 hours.

After filtration, the alcohol is evaporated, the distillation residue is taken up again with acidified water, the oily layer is collected in ether, and is then dried on calcium chloride and distilled. At 7277 C./20 mm. Hg, a fraction, 43.7 g., containing methyl 2,5-heptadienoate, is obtained. The distillation residue amounts to 2.1 g.

It is stated above that the main uses for the products are isomerization into conjugated products having known technological uses, and also through hydrogenation to produce esters of the corresponding saturated acids, having known uses in the arts as plasticizers.

For instance, the 5-methy1-2,5-hexadienoic acid and its esters are isomerized to 5-methyl2,4-hexadienoic acid upon heating or by saponification with sodium hydroxide. The corresponding S-phenyl compounds are similarly isomerized to 3,5-dienes.

The 2,4-acid esters undergo characteristics Diels-Alder condensation reactions. For instance, they can be utilized in the manner described in British Patent 569,113, namely by condensation with castor oil, to make modified drying oils. US. Patents 2,420,694 and 2,382,297 (Example 7) are also in point.

Another employment of the acids prepared by our process is to prepare copolymers with butadiene, which are useful for the production of resins.

Hydrogenation processes similar to those described in Chiusoli application Serial No. 765,734, filed October 7, 1958, can be used.

Moreover, many general uses for esters of fatty acids are known, as evidenced by the text, Kirt-Othmer, Encyclopedia of Chemical Technology.

We claim:

1. A process for preparing an alpha-beta, delta-epsilon, diene carboxylic acid ester, comprising reacting an allyl chloroderivative containing up to 20 carbon atoms, of the formula:

in which the R, R and R groups are taken from the class consisting of hydrogen, methyl, and homologues of methyl; with acetylene, carbon monoxide, and an aliphatic alcohol containing up to five carbon atoms, at 10 to +50 C., in the presence of metallic nickel and thiourea.

2. The process of claim 1, the nickel being Raney nickel.

3. The process of claim 1, the alcohol being an alkanol.

4. The process of claim 1, the nickel being provided by a mixture of subdivided iron and nickel chloride, the said mixture being present in the reaction mixture.

5. The process of claim 1, the hydrochloric acid developed in the process being neutralized as it forms.

6. The process according to claim 1, characterized in that the nickel needed for the reaction is obtained by reduction of nickel hydroxide in the liquid phase with hydrogen.

7. The process according to claim 4, 'wherein the finely divided iron is obtained by grinding metal iron followed by sieving on 16,000-mesh sieve.

8. A process of making an alkyl ester of 2,5-hexadienoic acid, comprising reacting allyl chloride with an alkanol having up to five carbon atoms, acetylene, and carbon monoxide in the presence of finely divided nickel and thiourea.

9. A process of making an alkyl ester of 5-methyl-2-,5- hexadienoic acid, comprising reacting methallyl chloride with an alkanol having up to five carbon atoms, acetylene, and carbon monoxide in the presence of finely divided nickel and thiourea.

10. A process of making an alkyl ester of 2,5-heptadienoic acid, comprising reacting crotyl chloride with an alkanol having up to five carbon atoms, acetylene, and carbon monoxide in the presence, of finely divided nickel and thiourea.

11. A process of making an alkyl ester of 8,8-dimethyl- 2,5-nonandienoic acid, comprising reacting 5,5-dimethyl- 2-hexenyl chloride with an alkanol having up to five carbon atoms, acetylene, and carbon monoxide in the presence of finely divided nickel and thiourea.

No references cited.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,032,583 May 1, 1962 Gian Paolo Chiusoli et a1. It is hereby 065%edthat error appears in the above numbered p atent requiring correction and that the said Letters Patent should read as corrected below.

In the heading to the printed specification II -Ti e 9, for "Sept. 29 1960" read Dec. 18 1959 Signed and sealed this 18th day of September 1962.

(SEAL) Attest:

ERNEST w. SWIDER DAVID LADD Attesting Officer Commissioner of Patents 

1. A PROCESS FOR PREPARING AN ALPHA-BETA, DELTA-EPSILON, DIENE CARBOXYLIC ACID ESTER, COMPRISING REACTING AN ALLYL CHLORODERIVATIVE CONTAINING UP TO 20 CARBON ATOMS, OF THE FORMULA: 